NASHVILLE, Tennessee — An environmental group wants federal regulators to withhold the licensing of a nuclear power plant along the Tennessee River unless the commission first takes into account flood and earthquake risks at the Watts Bar Unit 2 reactor.

The Southern Alliance for Clean Energy has filed a response with the U.S. Nuclear Regulatory Commission saying that NRC staff has disregarded a report saying that earthquake risk is now greater than what the reactor was originally designed to withstand.

The Tennessee Valley Authority, which operates the nuclear plant about 50 miles northeast of Chattanooga, issued a statement disagreeing with the earthquake risk.

The environmental group says the regulatory commission appears to be postponing its analysis of greater earthquake and flooding risks until after the reactor is licensed.

"If there is something that's related — a very important safety concern about earthquakes, seismic events and then subsequent flooding risks — why not address it and make sure things are being done properly before issuing the operating license?" asked Sara Barczak, the group's program director.

The group maintains that the lessons from the disaster at the Fukushima nuclear plant in Japan have been ignored.

The Fukushima plant had meltdowns after an earthquake triggered a tsunami in Japan. Wednesday marks the fourth anniversary of the quake and tsunami that killed nearly 19,000 people.

The environmental organization says post-Fukushima investigations show that the Watts Bar site is subject to greater earthquake and flooding risks than it is designed to withstand, and that is what it wants the NRC to consider before issuing the license.

"Now, we're not going to have tsunamis on the Tennessee River," Barczak said. "But we have dams on the Tennessee River. It's a very engineered river."

"Both units at Watts Bar Nuclear Plant are designed to withstand seismic events that are likely to occur in the east Tennessee region," The TVA said in its statement. "TVA has submitted all required information on seismic ?modeling to the NRC as part of the licensing process for Watts Bar Unit 2. The NRC's review of seismic issues relating to its Fukushima response is ongoing, and TVA agrees with the NRC's decision that licensing work on Watts Bar Unit 2 should continue."

The agency said it would comply with requirements once the NRC's evaluation of the new seismic information is complete and it maintained that the safety of its workers and communities surrounding its facilities is a top priority.